Open-end spinning devices with such rotor bearing arrangements are known in various different embodiments, and have been extensively described, for example in German Patent Publications DE 195 43 745 A1, DE 196 01 034 A1, DE 197 05 607 A1 or DE 41 17 175 A1.
For example, German Patent Publication DE 195 43 745 A1 describes an embodiment in which the spinning rotor is supported both radially and axially by means of a magnetic bearing arrangement. The magnetic bearing at the end of the rotor shaft described in German Patent Publication DE 195 43 745 A1 has a magnetic rotor ring as well as a magnetic stator ring. Here, the two magnetic rings are aligned magnetically in such a way that a bearing gap is created between them. To suppress the radial oscillations of the magnetically seated spinning rotor, which occur in particular during a starting phase, the stator magnet is furthermore seated with its movements limited in the radial direction. Here, the radial deflections of the magnetic stator ring are damped by a mechanical friction device.
However, it is disadvantageous with this known installation that the static charge, which in particular occurs during the spinning of synthetic materials in the area of the spinning rotor, cannot be dissipated in a defined manner, since the spinning rotor is electrically insulated from the grounded components of the open-end spinning device. This electric charge has an interfering effect on the spinning process.
In the open-end spinning device in accordance with German Patent Publication DE 197 05 607 A1, the spinning rotor is supported with its rotor shaft in the wedge gaps of a support ring bearing, and rests axially against an aerostatic bearing. The rotor shaft is made of carbide, at least in the area of the bearing surface which cooperates with the axial bearing.
Because of the electrically insulated bearing of the spinning rotor, it is also possible with this known bearing arrangement for a static charge of the spinning rotor to appear during spinning of synthetic material in particular, leading to disadvantageous effects on the spinning process. Even temporary unintentional contact between the rotor shaft bearing surface and the bearing plate of the axial bearing, made of a carbon material, cannot produce a sufficient removal of the charge.
An open end spinning device is furthermore known from German Patent Publication DE 196 01 034 A1, in which the spinning rotor is aerostatically seated both radially and axially. As with the above described bearing arrangements, the bearing arrangement in accordance with German Patent Publication DE 196 01 034 A1 also has the problem that a permanent electric insulation of the spinning rotor during the spinning operation is produced because of the air gap of the aerostatic bearing, and therefore no sufficient removal of the electrostatic charge created during spinning takes place.
The problem of insufficient grounding of the spinning rotor, in particular in the course of processing synthetic feed materials, is also present in bearing arrangements of open-end spinning devices, such as those known from German Patent Publication DE 41 17 175 A1. With these bearing arrangements, which per se have proven themselves in actual use, the radial seating of the rotor shaft is customarily provided by plastic-coated support rings. Since the rotor shaft has a non-conducting, for example oxide-ceramic, insert in the area of its axial support, this also leads to an electric insulation and therefore to a static charge buildup of the spinning rotor.